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[glibc/history.git] / math / w_tgamma.c
blob3ce6e77b490303ef458e81fdf03f04dbc56c7013
1 /* @(#)w_gamma.c 5.1 93/09/24 */
2 /*
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
6 * Developed at SunPro, a Sun Microsystems, Inc. business.
7 * Permission to use, copy, modify, and distribute this
8 * software is freely granted, provided that this notice
9 * is preserved.
10 * ====================================================
13 #if defined(LIBM_SCCS) && !defined(lint)
14 static char rcsid[] = "$NetBSD: w_gamma.c,v 1.7 1995/11/20 22:06:43 jtc Exp $";
15 #endif
17 /* double gamma(double x)
18 * Return the logarithm of the Gamma function of x or the Gamma function of x,
19 * depending on the library mode.
22 #include <math.h>
23 #include "math_private.h"
25 #ifdef __STDC__
26 double __tgamma(double x)
27 #else
28 double __tgamma(x)
29 double x;
30 #endif
32 double y;
33 int local_signgam;
34 y = __ieee754_gamma_r(x,&local_signgam);
35 if (local_signgam < 0) y = -y;
36 #ifdef _IEEE_LIBM
37 return y;
38 #else
39 if(_LIB_VERSION == _IEEE_) return y;
41 if(!__finite(y)&&__finite(x)) {
42 if (x == 0.0)
43 return __kernel_standard(x,x,50); /* tgamma pole */
44 else if(__floor(x)==x&&x<0.0)
45 return __kernel_standard(x,x,41); /* tgamma domain */
46 else
47 return __kernel_standard(x,x,40); /* tgamma overflow */
49 return y;
50 #endif
52 weak_alias (__tgamma, tgamma)
53 #ifdef NO_LONG_DOUBLE
54 strong_alias (__tgamma, __tgammal)
55 weak_alias (__tgamma, tgammal)
56 #endif